WatchedValue object is returned by some [[Trading Terminal]] methods. Using this object you can get/set value and be notified when the value is changed.

value()

Returns current value.

setValue(value)

Sets new value.

subscribe(callback, options)

1. callback is a function to be called when the value is changed
2. options is an object with the following properties:
   1. once - if it is true the callback will be executed only once
   2. callWithLast - if it is true the callback will be executed with the previous value (if available)

unsubscribe(callback)

Use the same function which you used in subscribe function to unsubscribe from the updates.